A TX cowboy goes to Ireland

And walks into a bar.
He said: I will pay anyone $500 cash, for drinking a case of beer - nonstop.
There was nobody to take the offer.
10 minutes later, the cowboy made the offer again. At that point, McGregor left the bar.
Again, there were no takers.
30 minutes later McGregor returned and ask the cowboy: Are you still on?
The cowboy ordered a case of beer and McGregor drank the 24 bottles nonstop.
The cowboy paid him the $500, but asked: Hey, where did you go for 30 minutes?
To that McGregor said: to the bar across the street. I wanted to try drinking a case nonstop to see if i could do it.